Search

Biochar can significantly affect plant nutrient absorption. In this study, peanut shell, corn straw and rice straw were used as raw materials to prepare biochar, which was modified by graphene. The effects of different biochar and their modified biochar on wheat nitrogen absorption in an agrotechnology park soil were studied by pot experiments, to provide theoretical reference for soil improvement and straw resource utilization. The results showed that adding graphene to soil alone had no obvious effect on wheat nitrogen absorption (P > 0.05). All four biochar treatments had the most obvious effect on the nitrogen absorption of wheat at 5% modification, and the nitrogen absorption capacity of each part was grain > stem and leaf > glume > root system. The content of total nitrogen and nitrate nitrogen in the soil increased the most when 5% modified biochar was added, which increased by 46.5%-96.9%, 119%-128%, respectively. After 5% modified biochar was added, ammonium nitrogen in the soil was added. [ABSTRACT FROM AUTHOR]

Mechanical vibrations and acoustic noise induced by air-conditioners are a widespread cause for concern. The magnetic levitation (maglev) central air-conditioner (CAC) system is a new type of air-conditioner system considered to be able to generate less vibration and noise. The performances of a maglev system and a regular CAC system, under normal operating conditions, were compared experimentally in the same room. For each CAC, the compressor vibrations and floor vibrations were measured and evaluated with reference to the guidelines of the Chinese National Standard GB/T 50355-2005, Standard of Limit and Measurement Method of Vibration in the Room of Residential Buildings. The indoor noise generated by each CAC system was also measured and compared. Results show that (1) in the frequency domain, the compressor vibrations of the maglev CAC are one to two orders of magnitude weaker than those of the regular CAC; (2) the dominant frequencies of the compressor of the maglev CAC are 125, 165, and 350 Hz, but there are no apparent characteristic frequencies for the regular CAC; and (3) the indoor acoustic noise generated by the maglev CAC is significantly weaker than that generated by the regular CAC, with A-weighted sound levels differing by 6.5 dB on average. [ABSTRACT FROM AUTHOR]